1. Field of the Invention
The present invention relates to a gas rate gyro set on a mobile object, such as a vehicle or a ship, to detect the rotatory motion of the mobile object and, more particularly, to a gas rate gyro which detects the angular velocity of a rotatory motion of a mobile object through the detection of a Coriolis force acting on an ionic wind generated in a casing.
2. Description of the Prior Art
The gas rate gyro measures the angular velocity of a mobile object through the measurement of a Coriolis force acting on a gas current. The gas rate gyro is features by the small number of component parts, low cost, high vibration resistance and capability of being set simply on a vehicle or the like.
Japanese Patent Laid-open (Kokai) No. 60-133369 discloses a gas rate gyro not having any mechanical functional component, such as a pump in which a gas is ionized in an electric field to generate a gas current. Japanese patent Laid-open (Kokai) No. 61-256216 discloses a similar gas rate gyro, in which a rare gas sealed in a glass case is ionized by a discharge to form a plasma, a plasma jet is formed in the rare gas by an annular accelerating electrode for attracting charged particles and an annular focusing electrode for focusing the jet of charged particles, and a Coriolis force acting on the plasma jet is detected. Japanese Patent Laid-open (Kokai) No. 58-71465 discloses a gas rate gyro, in which an ionic wind generated by a corona discharge is used as a pump for forming a jet of gas, the jet of gas is ionized by a radiation source, and the ions are detected.
Since the known gas rate gyro detects the angular velocity of a mobile object by using the plasma jet in a vacuum or in a rare gas, the flow speed of the plasma current, i.e., a current of ions, in the vacuum or in the rare gas is very high. It is known that the deflection of the current of ions subjected to the action of a Coriolis force is dependent on the flow speed of the current of ions; that is, the deflection Y is in inverse proportion to the flow speed of the current of ions, is in proportion to the square of the distance L between the electrodes and is in proportion to the angular velocity .omega. of the rotating mobile object. Thus, the current of ions is deflected by a Coriolis force acting thereon, and the deflection of the current of ions is in proportion to the flow speed of the current of ions. Since the flow speed of the current of ions in a high vacuum or in a rare gas is very high, the distance L between the electrodes must be very large to detect the deflection Y of the current of ions at a satisfactory accuracy, namely, to make the deflection Y large, which inevitably increases the size of the gas rate gyro. The gas rate gyro using radioactive rays entails injurious effect on the environment in the manufacture and use of the gas rate gyro.